Carboxylation of acetylenic compounds

ABSTRACT

Method of carboxylating a compound of the group of R-C CH, RCH2CN, indene, cyclopentadiene or fluorene, where R is hydrocarbyl, comprising contacting said compound with carbon dioxide under substantially anhydrous conditions in the presence of a base of the formula: WHERE X is sodium or potassium, R1 is hydrogen or alkyl and subsequently acidifying the resultant reaction product to form the carboxylated product.

United States Patent Patmore et al.

[ 1 Sept.5, 1972 CARBOXYLATION OF ACETYLENIC COMPOUNDS Inventors: EdwinL. Patmore, Fishkill; William R. Siegart, Poughkeepsie; Harry Chafetz,Poughkeepsie, all of N.Y.

US. Cl. ..260/515 R, 260/413, 260/533 A Int. Cl ..C07c 51/00 FieldofSearch ..260/5l5 R, 533 A,4l3

References Cited UNITED STATES PATENTS 9/1966 Kurtz ..260/533 PrimaryExaminer-lanes A. Patten Attorney-K. E. Kavanagh et al.

[57] ABSTRACT Method of carboxylating a compound of the group of R-C CH,RCH,CN, indene, cyclopentadiene or fluorene, where R is hydrocarbyl,comprising contacting said compound with carbon dioxide undersubstantially anhydrous conditions in the presence of a base of theformula:

where X is sodium or potassium, R' is hydrogen or alkyl and subsequentlyacidifying the resultant reaction product to form the carboxylatedproduct.

5 Claims, No Drawings C ARBOXYLATION OF ACETYLENIC COMPOUNDS This is adivision of Ser. No. 784,901, filed Dec. 18, 1968, now matured to U.S.Pat. No. 3,595,907.

BACKGROUND OF INVENTION SUMMARY OF INVENTION We have discovered a methodof carboxylating organic compounds of the group of RC 5 CH, RCH CN,indene, cyclopentadiene or fluorene, where R is alkyl, aryl, alkaryl andaralkyl of from one to carbons consisting essentially of contacting saidorganic compounds with carbon dioxide under substantially anhydrousconditions in the presence of a base of the formula:

where X is sodium or potassium and R is hydrogen or alkyl of from one tol2 carbons, and subsequently acidifying the resultant reaction mixtureto recover the carboxylic acid. The discovery that the sodium andpotassium phenoxide salts facilitate the production of carboxylatedproducts in high yields has rendered a base catalyzed carboxylationprocess for the starting materials contemplated herein commerciallyfeasible since the phenoxide is many times less expensive than theprevious bases employed.

DETAILED DESCRIPTION OF THE INVENTION Specifically, the inventionrelates to contacting essentially in the absence of water an activehydrogen containing organic compound of the group R-C E CH, RCH CN,indene, cyclopentadiene or fluorene with a phenoxide of the formula:

where R, R, and X are as heretofore defined with carbon dioxidepreferably in excess and subsequently acidifying the resultant mixtureto respectively form carboxyl compounds of the group of R-C E C- COOH,

COOH RT-ICN indene-3-carboxylic acid, tricyclo[5.2. I .0"]deca-3,8-diene-4,9-dicarboxylic acid and tricyclo[5.2.l.0"ldeca-3,8-diene-5,S-dicarboxylic acid, or fluorene-9- carboxylic acid.The carbonation advantageously takes place at a temperature betweenabout 0 and l50C., preferably between about 25 and 50C., under a carbondioxide pressure of between about l to 200 atmospheres, preferablybetween 1 and 25 atmospheres, utilizing a mole ratio of phenoxide toorganic compound of between about H and 20: l, preferably between H and5:], and an excess of carbon dioxide. Advantageously, the reactionmixture is acidified desirably at a temperature between about 5 and 35C.to a pH of less than 6, preferably between about 1 and 3, to insurecomplete conversion ofthe intermediate alkali metal salt to the desiredacid product. Although the reaction may be conducted in the absence ofsolvent, an inert liquid solvent is preferably used in amounts ofbetween about 50 and wt. percent of the reaction mixture. The use ofsolvent is desirable in order for the production of maximum productyields.

By the term substantially anhydrous a water content of less than about0.5 wt. percent based on the reaction mixture during carbonation isintended.

Examples of the organic reactant compounds contemplated herein arephenylacetylene, benzyl cyanide, acetonitrile, hexane-nitrile,acetylene, l-butyne and lhexyne.

Examples of the base constituents are potassium and sodium salts ofphenol, methylphenol, t-octylphenol, nonylphenol and dodecylphenol.

Specific examples of the acidifying acids contemplated herein are themineral acids such as hydrochloric acid, nitric acid, sulfuric acid andhydrobromic acid in aqueous concentrations ranging from 4 to 96 wt.percent.

Specific members of the inert liquid solvents conte mplated herein areN,N-dimethylformamide, hexamethylphosphoramide, dimethyl sulfoxide,diphenyl sulfoxide, dimethyl sulfone and N,N-dimethylacetamide. Thesolvent during the carbon dioxide contact advantageously constitutesbetween about 50 and 90 wt. percent of the reaction mixture.

During the carbon dioxide contact the gas is normally passed through thereaction mixture in a liquid state. However, alternatively, the organicreaction mixture may be sprayed into an atmosphere of carbon dioxide orthe carbon dioxide may be passed over a solid or liquid surface which isdesirably continually changed by agitation in order to form a freshsurface for contact.

The carboxylic acid products are recovered from the reaction mixture bystandard means such as selective extraction, distillation, decantationand combinations thereof. Specific examples of the carboxylic acidproducts contemplated herein are indene-3-carboxylic acid, tricyclo[5.2.l .0 ]deca-3,8-diene-4,9-dicarboxylic acid and tricyclo[5.2.l.0"]deca-3,8-diene-5,5- dicarboxylic acid, phenylpropiolic acida-phenylcyanoacetic acid, cyanoacetic acid, a-cyanohexanoic acid, 9-fluorene carboxylic acid, 2-butynoic acid, 2-propynoic acid andZ-hexynoic acid.

The following examples further illustrate the invention but are not tobe considered as limitations thereof.

EXAMPLE I This example illustrates the preparation of indene-3-carboxylic acid from indene.

To a three-necked round bottomed flask equipped with magnetic stirrer,thermometer, water cooled condenser and a gas sparger. the condenserconnected to a mercury bubbler to protect the system from atmosphere,3.5 grams of indene, l5.8 grams of potassium phenoxide, and 75 mls. ofdimethylformamide were charged. The resultant mixture had a watercontent of less than 0.5 wt. percent. An excess of dried carbon dioxidewas bubbled through the reaction mixture under atmospheric pressure overa period of 5 hours. At the inception of carbon dioxide introduction,the reaction mixture was at room temperature (about 26C.). Thetemperature increased from room temperature to 45C. within 5 minutesafter introduction. Within 8 minutes after introduction the temperaturedropped to 28C. and thereafter remained during the entire reactionperiod between 26 and 28C.

At the end of the 5-hour period the reaction mixture was poured into amixture of 80 mls. of concentrated hydrochloric acid and 100 grams ofice overlaid with I00 mls. of ether. The temperature of acidificationwas about C. The layers were separated and the aqueous layer extractedwith ether 100 mls.). The ether extracts were combined with the firstorganic layer. The combined ether organic layers were extracted, 10 wt.percent sodium bicarbonate (5X 100 mls) and the sodium bicarbonateextracts were then acidified (to a pH of l to 3) with 6M HCl whilekeeping the entire mixture cooled in an ice-water bath. The combinedacidified sodium bicarbonate extracts were then extracted into ether(SXlOO mls), dried and the ether removed on a rotary evaporator to givethe crude carboxylated product. Recrystallization of the crude productfrom benzene gave a yield of L79 grams ofindene-3-carboxylic acidcorresponding to a yield of 37.4 mole percent. The structure of theindene3-carboxylic acid product was confirmed by its melting point ofl57C. lit. l58-160C.) and its infrared and nuclear magnetic resonancespectra.

EXAMPLE II This is a description of the preparation of phenylpropiolicacid from phenylacetylene.

The carbon dioxide contact, acidification and recovery was the same asthat used in Example I with the following exceptions:

To the three-necked flask there was charged 3.! grams ofphenylacetylene, 15.8 grams potassium phenoxide and 75 mls. ofdimethylformamide. Upon charging of the first three reactants, thetemperature rose from 27 to 3lC. and the solution became dark brown. Thewater content therein was less than 0.5 wt. percent. Then dried carbondioxide in excess was bubbled into the mixture and the temperature roseto 43C. in 4 minutes and gradually returned to 32C. at the end of thefirst hour. The temperature held at 3 lC. for the next 2 hours. Totalcarbonation time was 3 hours at a temperature in the range of 31-43C.

The product after acidification and work-up was 1.6 grams ofphenylpropiolic acid representing a yield of 37 mole percent having amelting point of l37-l 38C.

(lit. m.p. l37-l39C.), a carbon content of 73.9 wt. percent (74 percentcalc.), a hydrogen content of 4.2 wt. percent (4.1 percent calc.) and aninfrared spectrum identical to phenylpropiolic acid.

EXAMPLE lll This example illustrates the preparation ofoz-phenylcyanoacetic acid from benzyl cyanide.

The procedure of Example I was essentially repeated with the followingexceptions:

To the reaction flask there was charged 3.5 grams of benzyl cyanide,15.8 grams potassium phenoxide, and 75 mls. of dimethylformamide. Theresultant mixture had a water content less than 0.5 wt. percent. Within3 minutes of charging the reactants to the flask the temperature rosefrom 31 to 45C. and dropped to 32C. over the next 19 minutes.Thereafter, the temperature during carbon dioxide bubbling remainedbetween 28 and 32C. for the reaction period. The total carbonation timewas 4 hours. The temperature ranged in this 4 hour period between 28 and45C.

After acidification and work-up a solid was recovered in an amount of2.7 grams and was determined to be a-phenylcyanoacetic acid in a yieldof 56 mole percent. The a-phenylcyanoacetic acid had a melting point of92.593.5C. (lit. m.p. 92C.) and infrared and nuclear magnetic resonancespectra which confirmed it to be a-phenylcyanoacetic acid. Elementa]analysis found 67 wt. C calc. 67), 4.3 wt. H (cal. 4.3) and 8.8 wt. N(calc. 8.7).

EXAMPLE IV This example illustrates the conversion of cyclopentadiene totricyclo[ 5.2. l .O ']deca-3,8-diene-4,9-dicarboxylic acid better knownas Thieles acid and a minor amount of tricyclo[ 5.2. l .0ldeca-3,8diene-5,5-dicarboxylic acid.

The procedure employed was that of Example I with the followingexceptions:

There were introduced into the reaction flask 3L6 grams potassiumphenoxide, 4.0 grams cyclopentadiene and mls. of dimethylformamide. Theresultant mixture had a water content of less than 0.5 wt. percent.During carbon dioxide contact the temperature ranged from 33 to 47C.over a period of 3 hours. The amount of carbon dioxide employed was inexcess of that required for the complete conversion of thecyclopentadiene reactant to the carboxylic acid derivative.

One product recovered after work-up was determined to be Thieles acid inan amount of 3.1 grams representing a 47 mole percent yield and having amelting point of 199-20lC. (lit. m.p. 197-199C.). lts nuclear magneticresonance and infrared spectra confirmed it to be Thieles acid. A minoramount of tricyclo[5.2.1.0"]deca-3,8-diene5,S-dicarboxylic acid was alsofound.

EXAMPLE V This example further illustrates the method of the inventionand is directed to a series of runs of the type found in Examples l-IVexcept sodium phenoxide is substituted for potassium phenoxide.

The test data and results are reported below in Table l:

This example illustrates the critically of the particular combination ofbase and organic reactant in the production of carboxylic acids.

The procedure employed is essentially that described in Example I. Thetest data and results are reported below in Table II:

TABLE II Reaction Conditions During C Addition Run Base. DMF Org. Temp,Time, COOH No.molc mls. React. C. Hrs. Prod. AA C H OK 75 p-NT 23-44 2.2None 01 BB I00 CH 28-38 4 None 0J9 CC 75 FL 23-27 5 None 0.12 DD [R40075 PA 27-30 2 None 004 BE NaOl-l 75 p-NT 32-40 4.8 None 0.24 FF C H ONaIOU ID 3l60 2 None 012 GG lR-40O ID 46-5l 8 None 0.06 (CO,-l[}0() psigjlR-4U0 Polystyrene quaternary amine pNT p-Nitrotolucnc CH CyclohexunnncFL Fluorenc PA Phcnylucctylgne ID lndcne As can be seen from the abovetable, substitution of organo and base reactants of a closely relatednature for those contemplated herein fail to produce a carboxylic acidderivative.

We claim:

1. A method of producing: R-C E C-COOH. where R is alkyl, aryl, alkaryland aralkyl of from one to 20 carbons, comprising contacting R-C CH,where R is as heretofore defined with carbon dioxide under substantiallyanhydrous conditions in the presence of the base of the formula:

where X is sodium or potassium and R is hydrogen or alk l of one to lcarbo s, at a tem e at re between abcl ut 0 and 150 C. under a carbondioxi de pressure between about I and 200 atmospheres utilizing a moleratio of base to organic compound of between about lzl and 20:],subsequently acidifying the resultant reaction mixture to a pH of lessthan about 6 and recovering the carboxylic acid compound from theacidified mixture.

2. A method in accordance with claim 1 wherein said acidifying isconducted to a pH of between about i and 3 3. A method in accordancewith claim 2 wherein said acidifying is conducted with hydrochloricacid.

4. A method in accordance with claim 3 wherein said CO contacting isconducted in the presence of between about 50 and wt. percentdimethylformamide.

5. A method in accordance with claim 4 wherein said carboxylic acidcompound is phenylpropiolic acid and said organic compound isphenylacetylene.

2. A method in accordance with claim 1 wherein said acidifying isconducted to a pH of between about 1 and
 3. 3. A method in accordancewith claim 2 wherein said acidifying is conducted with hydrochloricacid.
 4. A method in accordance with claim 3 wherein said CO2 contactingis conducted in the presence of between about 50 and 90 wt. percentdimethylformamide.
 5. A method in accordance with claim 4 wherein saidcarboxylic acid compound is phenylpropiolic acid and said organiccompound is phenylacetylene.